Making the wave observable in the double-slit experiment

In summary, Physicist Dr. Muthuna Yoganathan thought the wave function was just a calculation tool, which is the standard minimal interpretation of QM. But then she started doing her own versions of the double-slit experiment at home using a red laser, culminating in purchasing a smoke machine. With that, you can see the entire trajectory of the laser beam as it forms an interference pattern on a screen. This is in contrast to how the double-slit is usually presented, where the wave isn't visible, and the wave function is seen as a mathematical tool for making stochastic predictions.
  • #106
Quantum Waver said:
Going back to the first video, I have a naive question about measurement. Both the screen and the smoke act as measurements, but they don't destroy interference, even if one photon were emitted at a time. So why does using a detector cause decoherence? Is it because it's detecting photons in one specific location, or is it because the detector is a complex macroscopic object?

Debates around measurement, collapse and decoherence seem to confuse the issue as to exactly when and why a measurement destroys the interference pattern. If the environment is causing decoherence, then why does the smoke and screen still allow for an interference pattern?
Yes they do destroy interference. If the photon is scattered by the smoke or reflected off the screen, you can't coax interference out of it. The unscattered photons carry on interfering.

The environment only causes decoherence if the particle interacts with it. It can't do anything just by being.
 
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